CAREER: Examining bacterial filamentation as a mechanism for cell-to-cell spreading in an animal host

该奖项的全部或部分资金来自《2021年美国救援计划法案》(公法117-2)。细菌病原体对健康和农业构成持续威胁，更深入地了解细菌在活动物中的传播方式可以为未来的治疗提供依据。小的透明线虫提供了一个机会，可以直接在活动物的环境中可视化细菌的感染和传播，从而能够发现可能太难在哺乳动物等更复杂的动物中可视化的新机制。这项提议使用野生分离的微小线虫及其相关的微生物群来揭示新的宿主-微生物相互作用。它重点剖析了一种新的细胞内细菌在宿主细胞之间传播的机制，这是在细菌感染的野生线虫中直接观察到的。该项目的结果将作为确定这种细胞-细胞扩散的范例和控制它的遗传途径是否在其他细菌中保守的技术路线图，这可能为治疗细菌感染和控制环境细菌提供新的策略。早期阶段的本科生将对这一提议进行基于发现的研究，然后创建基于研究的STEM课程，在当地高中任教。这将在这些本科生中形成一个研究意识的循环，以帮助消除对STEM研究可及性的长期心理障碍，特别是在第一代大学生和来自低收入地区的学生中。本项目的重点是一种新的胞内细菌病原体，即在体内观察到的一种新的细胞间传播机制，即在其宿主球囊线虫Oscheius tiPulae中进行细胞间传播。在肠道细胞入侵后，巴氏杆菌从一种球状杆菌转变为丝状形态，以便侵袭多个邻近的上皮细胞。芽孢杆菌的丝状化需要糖脂途径，这是细菌用来检测营养丰富的环境的一种保守的葡萄糖感应途径。这项提议将调查这样一种假设，即阿特罗普芽胞杆菌使用营养感应来检测宿主细胞的入侵，抑制隔膜，并触发丝状化传播到邻近的肠道细胞。其具体目标是(1)通过基因表达分析、代谢物分析和细胞生物学剖析糖脂途径在控制丝状化中的作用；(2)通过确定侧生宿主膜的命运来了解萎缩性芽胞杆菌的感染过程，并确定促进丝状化的宿主因素；以及(3)创建一个基于实验室的研讨会，使用野生线虫采样来发现在丰富条件下丝状化的其他细菌和线虫的新的细胞内细菌病原体。这一最终的教育目标将让处于早期阶段的本科生进行研究，然后在当地高中教授他们的发现，使年轻学生更容易获得基于STEM的研究。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). Bacterial pathogens pose a continuing threat to health and agriculture, and a deeper understanding of how bacteria spread in a live animal can inform future therapies. Small transparent nematodes offer an opportunity to directly visualize bacterial infection and dissemination in the context of a live animal, allowing for the discovery of novel mechanisms that may be too difficult to visualize in more complex animals like mammals. This proposal uses wild-isolated, microscopic nematodes and their associated microbiota to uncover novel host-microbe interactions. It focuses on dissecting the mechanisms governing a new paradigm for intracellular bacterial spreading between host cells, which was directly observed in a bacteria-infected wild nematode. The results from this project will serve as a technical roadmap for determining whether this paradigm for cell-cell spreading and the genetic pathway that controls it are conserved among other bacteria, which could provide novel strategies for treating bacterial infections and controlling environmental bacteria. Early-stage undergraduates will conduct discovery-based research for this proposal and then create research-based STEM curriculum to teach at local high schools. This will create a cycle of research awareness among these undergraduates to help eliminate persistent psychological barriers about the accessibility of STEM research, especially among first-generation college students and those from low income areas. This project focuses on a new intracellular bacterial pathogen, Bordetella atropi, that was observed in vivo to use a novel mechanism for cell-to-cell spreading in its host nematode Oscheius tipulae. After intestinal cell invasion, B. atropi converts from a coccobacillus to a filamentous morphology in order to invade multiple neighboring epithelial cells. Filamentation by B. atropi requires the glucolipid pathway, a conserved glucose-sensing pathway used by bacteria to detect a nutrient-rich environment. This proposal will investigate the hypothesis that B. atropi uses nutrient sensing to detect host cell invasion, inhibit septation, and trigger filamentation for spreading to neighboring intestinal cells. The specific aims are to (1) dissect the role of the glucolipid pathway in controlling filamentation through gene expression analysis, metabolite analysis, and cell biology; (2) understand the infection process of B. atropi by determining the fate of the lateral host membranes and identify host factors that promote filamentation, and (3) create a lab-based workshop that uses wild nematode sampling to discover other bacteria that filament in rich conditions and new intracellular bacterial pathogens of nematodes. This final education aim will have early-stage undergraduates conduct the research and then teach their discoveries at local high schools, making STEM-based research more accessible to young students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.